Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would
be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate
that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views.
It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if
you would like to post something on RF Cafe's
page, please do.
Below are all of the forum threads, including all
the responses to the original posts.
Post subject: double quadrature detection
Posted: Thu Feb 03, 2011 10:51 am
Joined: Tue Nov 30, 2010 11:36 am
Does any one know her I can find a description/analysis of the so called double quadrature detector? This is basically two IQ detectors acting on the RF signal and on a 180 shifted version of RF. Then, you make 0-180 and 90-270, to get I and Q.
This is supposed to have better performance than the simple IQ detector, but I don't know why.
Post subject: Re: double quadrature detection
Posted: Thu Apr 28, 2011 4:30 pm
Joined: Mon Feb 25, 2008 4:53 pm
If I understand what you're talking about, a double quadrature converter is where basically where two sets of I/Q mixing paths are used. The I signal is mixed with the 0deg and 90deg LO signal to create basically an Ii and an Iq signal, and the Q path is mixed with the same 0deg and 90deg LO to create a Qi and a Qq signal. Then the Iq and the Qi are mixed to generate the Q output, and the Ii and Qq are mixed to generate the I output. What results is a cancelling of the image frequency in a way that is more broadband that when done only with diodes and transformers. I tried to find a good picture of it for you online but couldn't find anything.